STOCK-BASED COMPENSATION - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Aggregate Intrinsic Value ($ in millions)
Options Exercisable	$ 1.5	$ 4.4	$ 1.3
Stock Option
Number of Shares
Balance beginning of period (in shares)	753,038
Vested (in shares)	(102,645)
Forfeited (in shares)	(3,000)
Expired (in shares)	(13,800)
Balance end of period (in shares)	633,593	753,038
Options Exercisable (in shares)	633,593
Weighted Average Grant Date Fair Value
Balance beginning of period (in usd per share)	$ 10.96
Vested (in usd per share)	9.37
Forfeited (in usd per share)	13.74
Expired (in shares)	8.57
Balance end of period (in usd per share)	11.26	$ 10.96
Options Exercisable (in usd per share)	$ 11.26
Weighted Average Remaining Contractual Life	3 years 9 months 18 days	4 years 4 months 24 days
Options Exercisable, Weighted Average Remaining Contractual Life	3 years 9 months 18 days
Aggregate Intrinsic Value ($ in millions)
Aggregate intrinsic value, options outstanding	$ 1.3	$ 8.1
Exercised	1.5
Options Exercisable	$ 1.3

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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